The objective of this project is to elucidate the role of the intestinal macrophage in local immunoregulation of inflammatory states of the bowel. Studies are designed to characterize the synthetic and phagocytic properties of the intestinal macrophage in the guinea pig and human. A model is being developed with carrageenan-induced inflammatory bowel disease to define the effector changes in the macrophage population. Long-term culture of guinea pig peritoneal and intestinal macrophages will make it possible to study the secretory and phagocytic function in the resident and inflammatory population. Complement and lysozyme secretion as well as complement and IgG-mediated phagocytic activity will be studied. In the human, local immunoregulatory cells in the intestine are being assessed with in situ methods using monoclonal antibodies as probes. In the peripheral blood of patients with inflammatory bowel disease, the secretory function of the monocyte population is being evaluated and compared with monocytes from patients without inflammatory bowel disease. Peripheral monocyte function is being compared with local intestinal macrophage function.